CVE-2008-5313 in mailscanner
Summary
by MITRE
mailscanner 4.68.8 and other versions before 4.74.16-1 might allow local users to overwrite arbitrary files via a symlink attack on certain temporary files used by the (1) f-prot-autoupdate, (2) clamav-autoupdate, (3) avast-autoupdate, and (4) f-prot-6-autoupdate scripts in /etc/MailScanner/autoupdate/; the (5) bitdefender-wrapper, (6) kaspersky-wrapper, (7) clamav-wrapper, and (8) rav-wrapper scripts in /etc/MailScanner/wrapper/; the (9) Quarantine.pm, (10) TNEF.pm, (11) MessageBatch.pm, (12) WorkArea.pm, and (13) SA.pm scripts in /usr/share/MailScanner/MailScanner/; (14) /usr/sbin/MailScanner; and (15) scripts that load the /etc/MailScanner/mailscanner.conf.with.mcp configuration file.
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Analysis
by VulDB Data Team • 10/19/2018
This vulnerability represents a critical path traversal and symbolic link attack flaw affecting MailScanner versions prior to 4.74.16-1. The issue stems from insufficient input validation and improper handling of temporary files within multiple script components of the MailScanner email security suite. Attackers can exploit this weakness by creating malicious symbolic links in strategic locations, potentially allowing them to overwrite arbitrary files on the system with elevated privileges. The vulnerability affects a wide range of scripts including autoupdate mechanisms, wrapper scripts, and core MailScanner modules, making it particularly dangerous as it spans multiple attack vectors within the email security infrastructure.
The technical implementation of this vulnerability involves the manipulation of temporary file creation processes where scripts fail to properly validate or sanitize file paths before creating or accessing temporary files. When these scripts execute with elevated privileges, particularly in the /etc/MailScanner/autoupdate/ directory, attackers can establish symbolic links pointing to sensitive system files such as configuration files, binaries, or log files. This creates a race condition scenario where the legitimate script creates a temporary file that the attacker has already prepared as a symbolic link, resulting in unintended file overwrites. The vulnerability directly maps to CWE-367, which addresses Time-of-Check to Time-of-Use (TOCTOU) flaws, and CWE-22, which covers path traversal issues. The attack pattern aligns with ATT&CK technique T1059.007 for script execution and T1548.001 for privilege escalation through file permissions.
The operational impact of this vulnerability extends beyond simple file overwrite capabilities, as it can potentially lead to complete system compromise. When exploited against the core MailScanner binary or configuration loading scripts, attackers could modify critical system components or inject malicious code that persists across system reboots. The autoupdate scripts are particularly dangerous as they typically run with root privileges, creating a direct path for privilege escalation. Additionally, the wrapper scripts that interface with various antivirus engines could be compromised to redirect malware detection or even deliver malicious payloads. The quarantine and message processing modules represent another attack surface where compromised scripts could redirect or manipulate email content, potentially bypassing security controls entirely. This vulnerability affects organizations relying on MailScanner for email security, particularly those with complex email infrastructure where the software operates with elevated privileges.
Mitigation strategies should focus on immediate patching to version 4.74.16-1 or later, which addresses the symbolic link handling issues in all affected scripts. System administrators should implement proper file permissions and ownership controls, ensuring that temporary directories have restrictive permissions and are not writable by untrusted users. The principle of least privilege should be enforced by running MailScanner components with minimal required privileges, particularly the autoupdate scripts that currently operate with elevated permissions. Additionally, organizations should implement monitoring for suspicious file creation patterns and symbolic link manipulation in critical directories. Regular security audits should verify that temporary file handling in all MailScanner components follows secure coding practices, including proper validation of file paths and use of atomic file creation techniques. Network segmentation and intrusion detection systems should be configured to alert on unusual file modification patterns in MailScanner directories, particularly during scheduled update operations when the vulnerability is most exploitable.